Injection Parameters Affecting the Water Alternating Gas Injection Process: A Case Study of an Iranian Oil Reservoir

Much research has been recently conducted on how to enhance oil recovery using a wide range of parameters. To this end, the three oil recovery mechanisms including primary, secondary and tertiary mechanisms have been improved and extended in order to increase oil production. One of the tertiary recovery methods that enjoys high popularity is water alternating gas (WAG) injection process. This method is applied in the reservoirs which are under natural depletion, and benefit secondary mechanisms such as water injection. The main object here is increasing the oil recovery. This method could benefit the advantages of both water injection and gas injection. Since the sweep efficiency of gas is less than water, the gas flow in the upper reservoir has a lower density, and if during the water injection process the water is not the wetting phase (since the water does not flow upper), much of the oil in the reservoir, which is trapped between the rocks, cannot be obtained. By the same token, we combined water injection and gas injection methods, benefited the advantages, minimized the disadvantages, and called it water alternating gas injection (WAG).